Inflation of a truck tire, or a tire used on other types of larger vehicles, such as tractors, trailers, buses and off-road machines, is inherently hazardous undertaking unless proper precautions are taken. Tires used on such vehicles are much larger than automobile tires and are typically operated at higher inflation pressures (say about 50-55 psig); as a result, when a tire of this size bursts, there is the possibility of death or serious bodily harm for anyone standing in the trajectory of the tire, unless a proper safety cage or other restraining device is used. Also, an operator who is filling such a tire should be at a position remote from the tire itself, i.e., out of trajectory of the tire. Failure is typically in the tire sidewall. Such failure may occur in the tire sidewall. A common mode of failure is breaking or weakening of steel reinforcing cords. A common mode of failure of this type is a "zipper rupture," so called because of the resemblance of a tire ruptured in this manner to an open zipper. A common cause of such failure is use of the tire while either under inflated or overloaded.
The United States Occupational Safety and Health Administration (OSHA) has promulgated safety and health standards regarding the servicing of wheels and tires used on large vehicles such as trucks, tractors, trailers, buses and off-road machines. These standards are found at 29 CFR .sctn.1910.177. Briefly, these standards require all tubeless and tube-type medium and large truck tires to be inflated using OSHA-approved restraining device such as a safety cage or barrier, and using a clip-on air chuck with a pressure regulator and an extension air hose. The Rubber Manufacturers Association (RMA) of Washington D.C. goes further; it recommends that the OSHA procedures be applied to steel cord radial medium- and light-truck tires as well, and publishes bulletins explaining how zipper ruptures can occur and outlining recommended safety inspection procedures.